Management of thermal quantity of hydrogen and sulphur during combustion of Kosova s lignite

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1 AASCIT Journal of Energy 2014; 1(1): 1-6 Published online December 30, 2014 ( Management of thermal quantity of hydrogen and sulphur during combustion of Kosova s lignite Ahmet Haxhiaj, Nyrtene Deva, Mursel Rama Faculty of Geosciences, University of Mitrovica, Mitrovica, Republic of Kosovo address ahaxhiaj52@yahoo.com (A. Haxhiaj) Keywords Boilers, Combustion, Hydrogen, Sulphur, Thermal Received: November 29, 2014 Revised: December 20, 2014 Accepted: December 21, 2014 Citation Ahmet Haxhiaj, Nyrtene Deva, Mursel Rama. Management of Thermal Quantity of Hydrogen and Sulphur during Combustion of Kosova s Lignite. AASCIT Journal of Energy. Vol. 1, No. 1, 2014, pp Abstract The aim of paper is analyzing the issue related to the management of effective thermal quantity during lignite combustion and emissions of gases that are product of complete and non-complete combustion of lignite in the boilers. The real thermal amount of total burning lignite is 7524 kj kg -1. Thus, the losses of thermal quantity at ignition and during combustion of lignite directly depend on the diameter of lignite pieces intended for combustion. Paper contains the analyses of the thermal value, the composition of combustible and non-combustible matters of Kosova s lignite. The research on theoretical and practical field of management of thermal quantity of lignite is based and verified by DIN 1942, 1952, 1956 standards which describe effective thermal quantity. The paper reflects positively on management of the effective thermal quantity. 1. Introduction Boilers, combustion of lignite coal and its components in "Kosovo Energy Corporation" are basic processes for economic and environmental sustainability of Energetic Corporation. The paper discusses the combustion process of hydrogen and sulphur in oxidizing zone while is minimized the carbon combustion associated with hydrogen. The main subject of this paper is related to the chemical composition, power and thermal value of lignite coal which is 7524 kj kg -1 and depends on the percentage of carbon, hydrogen, sulphur, moisture and sterile parts. [1,2] In particular will be analyzed the balance of thermal quantity for hydrogen and sulphur, of Kosova lignite. During complete combustion of hydrogen is acquired the good utilization of thermal quantity and as product we have gases with minimal thermal quantity. Furthermore is analyzed the amount of thermal balance of sulphur combustion, whereas as products are benefited sulphur oxides and sulphur, also appears that the thermal amount is lost during the combustion process in boilers. With incomplete combustion we will have gases richer with carbon monoxide, hydrogen and sulphur, which carrying away the thermal quantity in environment, pollute the environment and reduce economic sustainability in the technological process in energetic corporations. [3,5,10] 2. The Composition of Fuel The main components of the fuel are carbon, hydrogen, sulphur, moisture and heterogeneous composition of oxygen, nitrogen and ash. The high content of moisture and ash in fuel, reduce its quality and is high impact factors for the quality determination [4].

2 2 Ahmet Haxhiaj et al.: Management of Thermal Quantity of Hydrogen and Sulphur during Combustion of Kosova s Lignite 2.1. Analytical Composition the Lignite Lignite as fuel is composed of non-combustible and combustible matters which determine its thermal value. Carbon in the fuel is a free and as such is determining the thermal value of the fuel, is also associated with hydrogen as methane, ethane, propane, etc. (2.1) C+H+O+N+S+W+A=100% (2.1) Based on the analysis such as experimental, analytical and XR, [2,5] which are realized at the Laboratory of Energetic Corporation of Kosovo, results that the Kosova's lignite has the average percentage of elements that are described in bellow table (2.1): Table 2.1. Average percentage of elements in lignite Element C H O N S W A Percentage % ,63 0,0100 0,63 40,7 14,8 3. Combustion of Lignite Combustion of the lignite coal is a complex process and includes 4 zones: heating zone, reductionzone, oxidation zone and ash zone. Oxidation combustion zone is subject of studying in this paper. During the complete combustion of lignite as products are obtained CO 2 and H 2 O, whereas during the incomplete combustion of lignite products are CO and H 2.[6,7] 3.1. Combustion of Hydrogen Hydrogen is matter that burns in fuels, is located as free and associated with other fuel elements. [6,8] Complete combustion of hydrogen is accomplished by reaction (3.1). H 2 + O= H 2 O H = kj. (3.1) To find the enthalpy for absolute combustion of one kilogram of hydrogen below expression is used (3.2): H H = x 100%/MWH kj/kg (3.2) 100%- is percentage of hydrogen associated with the oxygen (complete combustion of hydrogen) MWH- is molecular weight of hydrogen Hydrogen enthalpy for complete combustion is described through the expression (3.3). H H = x 100%/PMH= x 1//2= kj/kg (3.3) Alternative I with relative combustion, where 80% of hydrogen is related to oxygen, then enthalpy is described through the expression (3.4): H H = x 80%/PMH= kj/kg (3.4) Alternative II with low combustion, where 50% of hydrogen is related to oxygen, then enthalpy is described through the expression (3.5): H H = x 50%/PMH= kj/kg (3.5) To find the thermal quantity earned with combustion of hydrogen we use the expression (3.6): Q= m x H kj/h (3.6) m-weight of hydrogen H-enthalpy By 100% hydrogen combustion, the thermal amount earned is based in expression (3.7): Q=100% x H H = kj/h (3.7) Alternative I with 80% of hydrogen combustion, the thermal amount earned is realized according the expression Q =80% x H H = kj/h (3.8) Alternative II with 50% of hydrogen combustion, the thermal amount earned is realized according the expression (3.9) : Q =50% x H C = kj/h (3.9) 3.2. Combustion of Sulphur Sulphur as an element in the composition of lignite is matter that is burned and release thermal quantity, which should be well used in the process of lignite combustion in boilers. Sulphur in fuels is located as free and as sulphate, which is considered as mineral matter with negative effects on the quality of fuel and in the environment. [6,8] Combustion of sulphur becomes by the reaction (3.10): S+O 2 =SO 2 H =279 kj (3.10) To find the enthalpy for the complete combustion of one kilogram of sulphur is used the expression (3.11): H S = 279 x 100%/MWS kj/kg (3.11) 100% - is sulphur percentage associated with oxygen (complete combustion of sulphur). MWS- is molecular weight of sulphur To find the enthalpy for the complete combustion of one kilogram of sulphur is used the expression (3.12): H S =279 x 100%/PMS=279 x 1/32= kj/kg (3.12) Alternative I with relative combustion, where 80% of sulphur is associated with oxygen, then enthalpy is calculated through the expression (3.13): H S =279 x 80%/PMS= kj/kg (3.13) Alternative II with poor combustion, where 50% of sulphur is associated with oxygen, then enthalpy is is calculated through the expression (3.14):

3 AASCIT Journal of Energy 2014; 1(1): H S = 279 x 50%/PMS=43.53 kj/kg (3.14) To find the thermal amount earned during sulphur combustion the below expression is used (3.15): Q= m x H S kj/h (3.15) m-weight of sulphur, H S - enthalpy of Sulphur By 100% of sulphur combustion, the thermal amount earned is based in expression (3.16) : Q=100% x H S = kj/h (3.16) Alternative I with 80% of sulphur combustion the thermal amount earned is based in expression (3.17) : Q =80%x H S =55.8 kj/h (3.17) Alternative II with 50% of sulphur combustion the thermal amount earned is based in expression (3.18) : Q =50%x H S =21.76 kj/h (3.18) Table 3.1 and figure3.1, presents the data related the thermal quantity gained by combustion of hydrogen and sulphur Percentage of hydrogen and sulphur combustion (%) Weight of hydrogen and sulphur (kg) Table 3.1. Thermal quantity of hydrogen and sulphur combustion Enthalpy of hydrogen (kj/kg) Enthalpy of sulphur (kj/kg) Earned quantity for hydrogen (kj/h) Earned quantity for sulpfur (kj/h) Percentage of hydrogen and sulphur combustion (%) Enthalpy of hydrogen (kj/kg) Enthalpy of sulphur (kj/kg) Earned quantity for hydrogen (kj/h) Earned quantity for sulpfur (kj/h) 4. Balance of Thermal Quantity Analytical and graphical analysis of hydrogen and sulfur combustion in the oxidation zone, treating the management of the lignite combustion process in boilers in this zone [7,9]. Furthermore, is analyzed in details the thermal quantity Percentage of hydrogen and sulphur combustion (%) Figure 3.1. Thermal quantity of hydrogen and sulphur combustion Table 4.1. Changing of thermal quantity eraned with H and S combustion hydrogen combustion (kj/h) gained with combustion of hydrogen and sulpur and is proven to have different values. This changing of thermal quantity is the potential for losses, or thermal quantity without the well managed of process of lignite combustion in boilers. The data related to this issue are presented in table 4.1 and figure 4.1. sulphur combustion (kj/h) Changing of thermal quantity (kj/h)

4 4 Ahmet Haxhiaj et al.: Management of Thermal Quantity of Hydrogen and Sulphur during Combustion of Kosova s Lignite Percentage of hydrogen and sulphur combustion (%) hydrogen combustion (kj/h) sulphur combustion (kj/h) Changing of thermal quantity (kj/h) Based on the analysis of sulphur and hydrogen combustion and thermal value gained with their combustion, and the thermal value of the lignite basin of Kosovo is treated the thermal amount gained with complete and incomplete combustion of hydrogen and sulphur. Furthermore is treated Figure 4.1. Changing of thermal quantity earned with H and S combustion Table 4.2. Remaining quantity of the thermal value of H and S during combustion the remaining quantity of the thermal value,which is unused during the technological process of hydrogen and sulphur combustion in oxidizing zone that is potential for losses and for environmental pollution. The data related to this issue are presented in table 4.2 and figure 4.2. Percentage of H and S combustion (%) H and S weight (kg) Remaining thermal quantity of H Remaining thermal quantity of S (kj/h) (kj/h) Percentage of H and S combustion (%) Remaining thermal quantity of H (kj/h) Remaining thermal quantity of S (kj/h) Figure 4.2. Remaining quantity of the thermal value of H and S during combustion 5. Impacts of Sulphur and Hydrogen in the Environment Sulphur and hydrogen in Kosova s lignite, during the combustion process release the thermal amount that is managed to be transformed into electricity. The combustion process of sulphur and hydrogen in boilers is inclined to the formation of gases, especially the oxide gases. [5,8] Oxide gases of sulphur, occupying a special place in this paper related to the treatment, management and their impact on the environment. The main characteristics of sulphur and hydrogen in normal conditions 1. Sulphur a) The melting point o C, b) The boiling point o C, c) The starting point of melting o C, d) The critical point o C,

5 AASCIT Journal of Energy 2014; 1(1): e) The powder density kg/m 3, f) The molar volume cm 3, g) The thermal conductivity W/m K. 2. Hydrogen h) The melting point o C, i) The boiling point o C, j) Density of powder hydrogen 8.99 kg/m 3, Table 5.1. Melting point and thermal conductivity of S and H k) Molar volume - is associated with air, l) The thermal conductivity easy combustion The main parameters of the elements that result in the creation and emission of gases, that polluting the environment are the melting point and thermal conductivity table 5.1 and figure 5.1. Element Melting point ( 0 C) Thermal conductivity (W/m K) Sulphur Hydrogen Easily combustion 5.1. Enthalpy of Elementary Sulphur and Hydrogen The presence of sulphur and hydrogen in the environment as products of coal combustion in boilers, have their multi impacts on the environmental ecology. Based on the physical and chemical properties, and technological process of hydrogen combustion, is minimized the impact of hydrogen Figure 5.1. Melting point and thermal conductivity of S and H Table 5.2. Enthalpy of S and H kj kg -1 on the environment. Enthalpy for sulphur. Enthalpy of fusion (mixture) is 1.73 kj mol -1. Enthalpy of evaporation is 9.8 kj mol -1. Enthalpy of powdering is 279 kj mol -1 (table 5.2 and figure 5.2). The hydrogen enthalpy. Enthalpy of mixture is minimized. Evaporation enthalpy is minimized. [3, 4] Enthalpy of powdering is kj mol-1. (table 5.2). Element Mixture Enthalpy kj kg -1 EvaporationEnthalpy kj kg -1 Powder Enthalpy kj kg -1 Sulphur Hydrogen Figure 5.2. Sulphur and hydrogen enthalpy kj kg Conclusion The paper analyzes the effective thermal value that depends on the percentage of combustion matters and necessary amount of air entered in technological process for the lignite combustion process. In particular in this paper is analyzed the thermal amount that is gained with the complete and incomplete combustion of hydrogen and sulphur, as well and gases released in the oxidation zone during technological process. As a result of analytical and graphical analyzes, led us to conclude that with the complete hydrogen combustion the thermal amount earned is kj / h, while with the complete sulphur combustion the thermal amount earned is

6 6 Ahmet Haxhiaj et al.: Management of Thermal Quantity of Hydrogen and Sulphur during Combustion of Kosova s Lignite kj / h. Grounded on the thermal value and its use during the combustion of hydrogen and sulphur, and obtained results will be an overview as follows. With complete combustion of hydrogen use of the thermal value of coal is comprehensive and has an average value of 4.12%. While with the complete combustion of sulphur, use of the thermal value of the coal is weaker and has an average value of 0.297%. It can be concluded, that with the complete hydrogen combustion, we will have a good use of the thermal quantities during the combustion process of the coal. Complete combustion of sulphur which results with lower thermal value, does not have any major impact on the thermal amount of lignite combustion process in boilers. Sulphur and its oxide gases have huge impact on environmental pollution. The paper as such reflects positively on the management and utilization of the thermal amount in the oxidation zone of boilers and closely is associated to positive effects on the economic and environmental sustainability. References [1] Ekrem B, (1987) Tehnologija sa poznavanje robe. Pejë, [2] Laboratory of Energetic Corporation of Kosovo [3] Feretič D,Tomišič Z, Śkanata D, Čavlina N, Subašič D (2000) Elektrane i okoliš. Zagreb, [4] Halili A, (1983) Furrat metalurgjike II. Tirane, [5] Haxhiaj A, Elezi D, Shkololli SH. (2006) Mjedisi dhe menaxhimi i gazrave termike në zonën e parangrohjes të furrave vatërxhakete në Trepçë simpoziumi i gjashtë ndërkombëtar Tirane. [6] Haxhiaj A, and Haxhiaj E, (2010) The Thermal Gas Processing in Pre-Heating Zone of Water-Jacket Furnaces in Trepça, TMS Annual Meeting & Exhibition, Seattle Washington, [7] Haxhiaj A, and Haxhiaj E, (2010) The Optimization of the Coke and Agglomerate Quantity in Lead Production in Water-Jacket Furnace, TMS Annual Meeting & Exhibition, Seattle Washington, [8] Haxhiaj A, and Haxhiaj E, (2010) The Air Pollution from the Port-Piri Furnaces Gases, Journal of International Environmental Application & Science, [9] Panariti A, Merollari J, (1987) Metalurgjia e gizës-2. Tirane, [10] Ranko R, (2010) Komercijalno Poznavanje robe. Beograd,